feat(S9/S8): bank-generation change-detection + instrument-side assignment reader

Extension stamps a monotonic bank_generation counter, bumped at content
mutations; the VST3 instrument polls it off-thread on an editor timer and
consumes assignment requests, refreshing playback hands-free.

src/actions.cpp

@@ -645,7 +645,9 @@ void doBankDelete() {
         ShowConsoleMsg("ReaSampler: cannot delete that bank (the pool is un-deletable).\n");
         return;
     }
-    persistBankOp("ReaSampler: delete bank");
+    // S9: bump only when the deleted bank held samples — dropping them changes what a live
+    // instance referencing one could play. Deleting an EMPTY bank is purely organizational.
+    persistBankOp("ReaSampler: delete bank", /*bumpGeneration=*/members > 0);
 }
 
 // Evacuate a named bank: move every member back to the pool (index-only, collapse by
@@ -666,7 +668,8 @@ void doBankEvacuate() {
                        "destination, not a source).\n");
         return;
     }
-    persistBankOp("ReaSampler: evacuate bank");
+    // S9: evacuate moves members between banks (bank membership changes) -> bump.
+    persistBankOp("ReaSampler: evacuate bank", /*bumpGeneration=*/true);
 }
 
 // Cycle the active bank forward in ordinal order (pool -> named -> ... -> pool),
@@ -752,7 +755,9 @@ void doBankTransferSelected(bool copy) {
     if (mutated) {
         const std::string label =
             std::string("ReaSampler: ") + verb + " sample(s)";
-        persistBankOp(label.c_str());
+        // S9: a move/copy changes bank membership (a sample arrives in / leaves a bank an
+        // instance may reference) -> bump so assigned instances refresh hands-free.
+        persistBankOp(label.c_str(), /*bumpGeneration=*/true);
     }
 }
 
@@ -794,7 +799,9 @@ void doBankRemoveSelected() {
     }
 
     // No-op guardrail (R-B): open an undo point only if the index actually mutated.
-    if (removed > 0) persistBankOp("ReaSampler: remove sample(s)");
+    // S9: a remove drops a sample from a bank (an instance referencing it must refresh — it
+    // will resolve to silence, per the stale-id policy) -> bump.
+    if (removed > 0) persistBankOp("ReaSampler: remove sample(s)", /*bumpGeneration=*/true);
 }
 
 // Prune bank folder — Phase R (Reclaim), R3: the guarded DESTRUCTIVE step, and the SOLE
@@ -884,8 +891,14 @@ void doBankPruneFolder() {
 // change stands and persists on the user's next save; it just earns no undo point until
 // there is a project to persist into (undo of an unsaved bank op has nothing to roll
 // back to anyway). The Begin/End must still be balanced, hence the close-either-way.
-void persistBankOp(const char* label) {
+void persistBankOp(const char* label, bool bumpGeneration) {
     Undo_BeginBlock2(nullptr);
+    // S9: bump the bank-generation counter INSIDE the block, before persistBook(), so the
+    // fresh generation rides the same ext-state write the persist makes (persistBook() ->
+    // saveToActiveProject() stamps bankGeneration()). Bumped only for content-changing verbs
+    // (the caller decides); a pure-organizational verb passes false and leaves the counter be,
+    // so a rename/activate does not needlessly refresh live instances.
+    if (bumpGeneration) g_session->bumpBankGeneration();
     const bool persisted = persistBook();
     if (persisted)
         Undo_EndBlock2(nullptr, label, UNDO_STATE_MISCCFG);